This guideline applies to combined heat and power systems (CHP systems) with a fuel input of up to 70 kW (referred to the net calorific value), designed for use in residential buildings. It covers single-family houses for up to 12 occupants and multi-family houses with up to 40 flats. The guideline supplies reference load profiles as a basis and tool for the designing of combined heat and power systems in residential buildings and for their cost-effectiveness analysis. Test conditions for the determination of the system efficiency, design criteria and testing procedures may be derived from this guideline. Furthermore, the guideline can be used for simulations and design calculations. Operating times and operating cycles can be used for the determination of service lives and maintenance intervals.